Worldwide, breast cancer (BC) is the most frequently occurring cancer in women. Each year, approximately 1.15 million cases and 410 000 deaths from BC are reported globally. Over recent decades, considerable interest has emerged regarding whether vitamins and/or other supplements can lower the risk of BC.
Because a hallmark of any cancer is faulty response to and repair of DNA damage, DRC was a logical covariate 
for the current study. Multiple studies have confirmed that low DRC correlates with increased cancer risk. The previously mentioned study by Matta et al showed that a low DRC was an important risk factor for BC. The study by Matta et al (2012) was carried out using the same cohort of women that was the basis of the ancillary study reported here.
People vary in their DNA-repair efficiency and capacity, and those inherent sensitivities to mutagens and carcinogens are increasingly being linked to polymorphisms in genes related to DNA repair. Although such small changes in gene sequencing as analyzed in that study may not cause cancer, they can predispose people to a higher risk of developing cancer. That predisposition means that modifying interactions among gene risk factors could play an important role in modifying cancer risk. If taking a multivitamin or calcium can decrease BC risk, then the topic is worthy of study from both health and financial standpoints.
Participants were 836 women recruited primarily from the private practices of oncologists, gynecologists, and surgeons in Puerto Rico. Intervention(s): A total of 312 individuals in the breast cancer (BC) group and 524 individuals in the control group were compared for their multivitamin and calcium intake, DRC levels, and other covariates.
The current investigation is the first of its kind to address all three of the following questions: (1) is multivitamin and/or calcium intake associated with BC, (2) is multivitamin and/or calcium intake associated with DRC, and (3) is intake of multivitamins and/or calcium independently associated with BC or indirectly associated with BC by potentially influencing DRC?
Source: Breast Cancer and DNA Repair Capacity: Association With Use of Multivitamin and Calcium Supplements, by Yeidyly Vergne, Dr PHc; Jaime Matta, PhD et al. Integrative Medicine, A Clinician’s Journal Vol. 12, No. 3
